Recently suggested is an art of forming wires by an ink jet method, not by using photolithography. In this art, for example, as disclosed in Japanese Publication of Unexamined Patent Application, Tokukaihei, No. 11-204529 (published Jul. 30, 1999), a substrate has an affinity area having affinity for a raw material of wires, and a non-affinity area having no affinity for the raw material of the wires, and the wires are formed by applying (adhering) droplets of the raw material of the wires onto the affinity area on the substrate by the ink jet method (hereinafter, the term “applying” includes meaning of “dropping” and “jetting”).
Note that Japanese Publication of Unexamined Patent Application, Tokukaihei, No. 11-204529 corresponds to U.S. Patent Publication No. 2003/0003231 A1.
Moreover, Japanese Publication of Unexamined Patent Application, Tokukai, No. 2000-353594 (published on Dec. 19, 2000) discloses an art of similarly forming wires by the ink jet method, in which banks are formed on both sides of a wire formation area so as to prevent a raw material of the wire from overflowing out of the wire formation area, upper parts of the banks having non-affinity for liquid (dewetting property), and the wire formation area having wetting property.
Note that Japanese Publication of Unexamined Patent Application, Tokukai, No. 2000-353594 corresponds to European Patent Application, No. EP 0989778 A1.
Moreover, disclosed in SID 01 Digest, pages 40 to 43, 6.1: Invited Paper: “All-Polymer Thin Film Transistors Fabricated by High-Resolution Ink-jet Printing” (written by Takeo KAWASE, et al.) is an art in which a TFT is formed by using only an organic raw material by using an ink jet method.
In this art, after a strip made of polyimide is formed in a channel section of the TFT by photolithography, a raw material of electrodes (electrode raw material) made of a conductive polymer is printed on both sides of the channel section by using an ink jet printer. Because the strip made of polyimide has dewetting property, source and drain electrodes are formed respectively on the both sides of channel section, with no electrode raw material covering the strip.
The following explains a problem to be solved in the present invention.
When the arts of forming wires and the like by the ink jet method are adopted in manufacturing of a thin film transistor, a number of masks to need is reduced, and thus a number of steps in manufacturing process is reduced, compared with a case where the photolithography is used. Moreover, because a large-scale processing apparatus for forming the wire and the like is no longer necessary, cost of equipment is lowered. Those lead to cost-down.
Therefore, it is advantageous to adopt, in manufacturing of the thin film transistor, the art of forming the wire and the like by the ink jet method, because of the benefits given by the use of the art.
However, in case where simply the ink jet method is used to form the source or drain electrode of the thin film transistor by dropping (applying) droplets of the raw material of the electrodes in an area in which the source or drain electrode is to be formed, there is a possibility that a droplet (splash droplet) splashed in jetting may adhere on the channel section in the thin film transistor and remain thereon.
In this case, leakage may occur between the source and drain electrodes due to the slash droplet adhered on the channel section, or the splash droplet may work as a mask in processing an n+ layer so that the n+ layer is remained so as to allow a leak current to flow between the source and drain electrodes, thereby failing to obtain desired TFT characteristics.